Process for monitoring the wear of at least one contact in a switching device and switching device designed thereof

Abstract

A switching device including a measuring means for monitoring contact erosion, which is provided between a contact element and an associated contact support. The switching device includes an electrically insulated signal line, which is usable in individual and/or multiple contacts, is used as the measuring means, the signal line being integrated into a single monitoring circuit. In the switching device, there is arranged, between at least one of the contact elements and the associated contact support or in the contact material, an electrical conductor with insulator as the signal line, damage to or destruction of the insulator and/or the conductor being utilized to generate an external signal as an indication of the end of the service life of the contact element.

What is claimed is: 
     
       1. A switching device, comprising: a housing;   a contact element mounted in the housing on a contact support; and   an electrically insulated signal line for monitoring contact erosion,   wherein, when the electrically insulated signal line is damaged, an external signal is generated indicating that a service life of the contact element has ended, and   wherein the electrically insulated signal line is guided in a U-shape between the contact element and the associated contact support.   
     
     
       2. The switching device according to claim 1, wherein, in a multiple phase system with a neutral conductor, the electrically insulated signal line is connected to one of a neutral conductor and to another phase via an indicating device and via an associated protective resistor. 
     
     
       3. The switching device according to claim 1, wherein the electrically insulated signal line is extended in a U-shape over an entire rear side of the contacting element,   wherein a first end of the electrically insulated signal line is coupled to one of a neutral conductor and to another phase via a resistor, and   wherein a second end of the electrically insulated signal line is connected to the contact support via an indicating device.   
     
     
       4. The switching device according to claim 1, wherein the associated contact support is a fixed contact support that is utilized for indicating purposes. 
     
     
       5. The switching device according to claim 1, wherein the contact element has a rear-side soldering surface with a groove on the rear-side soldering surface, and wherein the electrically insulated signal line extends in a U-shape. 
     
     
       6. The switching device according to claim 1, wherein the electrically insulated signal line includes and insulator being composed of one of a glass-fiber sheath and another temperature-resistant insulator. 
     
     
       7. The switching device according to claim 5, wherein the groove has a height for indicating a remaining amount of a freely selectable remaining service life of the plurality of contact elements. 
     
     
       8. The switching device according to claim 5, wherein the switching device is one of a contactor and a circuit breaker. 
     
     
       9. The switching device according to claim 1, wherein the electrically insulated signal line that is guided in a U-shape includes a U-shape loop and two supply leads insulated from one another. 
     
     
       10. The switching device according to claim 9, wherein the U-shaped loop is guided in an insulated manner in a metal-sheathed tube. 
     
     
       11. The switching device according to claim 10, wherein the U-shaped loop in the metal-sheathed tube is implemented as an ungrounded sheathed thermocouple. 
     
     
       12. The switching device according to claim 11, wherein a first lead of the two supply leads coupled to the U-shaped loop is connected to one of the neutral conductor and a different phase via a protective resistor, and wherein a second lead of the two supply leads is connected to the associated contact support via an indicating device.